diff --git a/utils/stringv.c b/utils/stringv.c
index fadb5ce..e032a52 100644
--- a/utils/stringv.c
+++ b/utils/stringv.c
@@ -17,6 +17,7 @@
  */
 
 #define _POSIX_C_SOURCE 200809L // for strdup
+#define _BSD_SOURCE             // for strdup on old systems
 
 #include <stdio.h>
 #include <stdlib.h>